1. Field of the Invention
The invention relates to an electronic apparatus and, more particularly, to an electronic apparatus in which a detachable IC card is connected to an IC card junction portion and a CPU bus of the electronic apparatus main body is connected to the IC card by the junction portion and the IC card is used as an external memory device.
2. Related Background Art
FIG. 8 shows an external view of a conventional data processing apparatus such as personal computer, word processor, or the like and an IC card which is used as a small external memory device for the data processing apparatus.
A construction of a data processing apparatus 90 shown in FIG. 8 is used in a word processor, a personal computer, or the like and has a display 68 comprising an LCD panel or the like and a keyboard 86 as user interface means. The apparatus 90 also has an IC card 50 as an external memory device. Reference numeral 91 denotes an eject lever to remove the IC card 50.
As shown in FIG. 9, a control system of the data processing apparatus 90 comprises: a CPU 65; various control circuits which are connected to a data/address bus of the CPU 65; the display 68; a power source (P/S) section 84; and the key input section 86.
The IC card 50 is connected through an IC card connector 60 in a slot which is formed in the side wall of the keyboard 86 in FIG. 8.
The IC card is used as a memory area to store processing data of the apparatus main body, operation data or KANJI (Chinese characters) font data which has already been stored in the card, or data of utility softwares, or the like.
A plurality of read only memories (ROMs) 54 and a plurality of random access memories (RAMs) 55 are enclosed in the IC card 50 and are connected to the IC card connector 60 through a buffer 53 and a junction portion 51 by an address/data/control bus 56.
The address/data/control bus of the data processing apparatus 90 and signal lines of a power source and the like are also connected from the apparatus main body to the IC card connector 60 through a buffer 62 as necessary as shown in FIG. 10. The signal is connected to the IC card 50 by the connector.
To the address/data/control bus of the CPU 65, there are connected: a KANJI (or Chinese characters) ROM 69; a DMA controller 70; an RAM 82; an ROM 83; a timer 81; an I/O controller 71; a display controller 66 to control the input/output operation for the display 68 and keyboard 86; a key input controller 85; and the like.
An external expansion bus connector 89 is provided on the rear wall (not shown in FIG. 8) of the main body. A hard disc or an external control unit can be connected to the external expansion bus connector 89 through an exclusive control board and can be used to expand the external memory or to control the apparatus.
In recent years, the realization of miniaturization of the apparatus is more and more progressed. In the apparatus as mentioned above, it is becoming impossible to provide a space enough to attach both the connector 60 for the IC memory and the external expansion bus connector 89. For instance, there are also commercially available a portable data processing apparatus and the like such as IC card system pocket book, IC card electronic calculator, and the like having a small space only for providing a connector terminal for the IC card.
On the other hand, in such an apparatus as well, a high function such as a high processing speed to input/output data from/to an external apparatus or the like is required similarly to the case of a desktop type personal computer or the like.
As mentioned above, however, in recent years, it is difficult to assure an installation space of the connector to input/output for an external device. In the conventional construction, there is a case of a countermeasure such that the control of the external device and data input/output operation are executed or the like by using a serial communication connector. This is because an installation space for the serial communication connector is smaller than that for the external expansion bus connector since the serial communication connector has only a signal line.
According to the above method, however, the high-speed input/output operation cannot be executed by the communication using the serial communication connector. Such a method can be used for only an interface with a relatively low-speed external device such as printer, analog modem, or the like. It is difficult to apply the above method to an application field such that the memory of the IC card of a small capacity is expanded by connecting an external memory or the like.